This invention relates generally to lift platforms for supporting and raising persons or objects to an elevated position. More particularly, this invention pertains to lift platforms which are mountable in vehicles.
The prior art discloses a variety of portable lift platforms, each of which is intended to be mounted on a truck or trailer bed. For example, U.S. Pat. No. 2,945,551 of Annin et al. shows a portable platform elevating device with a stacked scissor-type lifting apparatus denoted as "lazy tong frames". The lifting apparatus is supported on the bed of a flat bed truck, and is lifted by three sets of hydraulic cylinders. Two sets of cylinders operate in the horizontal plane, and one set generally in the vertical plane. When folded down, the platform is suspended in the air at about cab height.
U.S. Pat. No. 3,664,459 of Stephens et al. describes a somewhat similar lift platform which is elevated from a position above a pickup truck cab. A single hydraulic ram drives the multiple scissor linkage lifting framework from a base bolted to the truck.
One problem with such lifting devices is that when the platform is at its lowest level, it is too elevated above ground level for loading heavy or bulky items thereon without the use of another lifting device such as a front end loader.
Common prior art truck mounted lifting devices which are permanently attached to a truck cannot be easily used to transport a significant quantity of other materials, because of the lengthy time required to detach and remove the device.